Kill Me More Times, I'll Become Invincible - Chapter 7:

When a cold and crafty girl travels into the body of a foolish, man-crazy, young female aristocrat, what will happen?

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.

After the hard struggle of a post-80s Shen Feiyang, he met with a tragic car accident in his fifties. When he again opened his eyes, he did not see the white walls of a hospital, nor had he arrived at the netherworld. Instead, he had transmigrated into the body of the post-50s young girl, Shen Yunfang.He had transmigrated into an era where people could not get enough to eat or sufficient clothes to wear.Humph, such hardships could not defeat a wise woman who had battled through society for half her life. Watch as she, with a chicken in her left hand and a duck in her right, carries a chubby baby on her back and sings triumphantly along the way.